1. Field of the Invention
The present invention relates to a communication system. More particularly, the present invention relates to a method and a system for configuring a frame in a communication system.
2. Description of the Related Art
Next generation communication systems are being developed that are capable of guaranteeing the mobility and Quality of Service (QoS) for Broadband Wireless Access (BWA) communication systems, such as a Wireless Local Area Network (WLAN) system and a Wireless Metropolitan Area Network (WMAN) system. An example of such communication systems includes an Institute of Electrical and Electronics Engineers (IEEE) 802.16e communication system.
The IEEE 802.16e communication system is a communication system employing an Orthogonal Frequency Division Multiplexing (OFDM)/Orthogonal Frequency Division Multiple Access (OFDMA) scheme in order to support a broadband transmission network for a physical channel of the wireless MAN system.
Further, the IEEE 802.16e communication system uses a time division multiple transmission scheme in order to support various transmission methods. The time division multiple transmission scheme transmits a preamble at each frame, which enables a user to access the system with minimum delay at an initial access stage. Further, the time division multiple transmission scheme can support an optimum transmission scheme for a given situation of a user through various services divided by time.
FIG. 1 illustrates a structure of a frame in a conventional communication system. The example shown in FIG. 1 corresponds to a Time Division Duplex (TDD) frame structure.
Referring to FIG. 1, the frame includes a downlink (DL) sub-frame 100 and an uplink (UL) sub-frame 150. The DL sub-frame 100 includes a preamble area 110, a Frame Control Header (FCH) area 120, a MAP area (i.e. DL-MAP/UL-MAP area) 130 and DL burst areas 140-1 to 140-5. The UL sub-frame 150 includes a UL control area 160 and UL burst areas 170-1 to 170-3.
Within the preamble area 110, a preamble signal is transmitted for synchronization between a signal transmission apparatus (e.g. a base station) and signal reception apparatuses (e.g. mobile stations). The FCH area 120 carries an FCH, which includes information on a length of the MAP area and a modulation scheme applied to the MAP area.
In the DL-MAP/UL-MAP area 130 a DL-MAP message and a UL-MAP message is transmitted, which include information on whether there are DL burst areas and UL burst areas allocated to each mobile station, and information on locations and modulation scheme applied to the DL burst areas and UL burst areas when there are DL burst areas and UL burst areas allocated to each mobile station. Since it is required that all mobile stations be able to receive the DL-MAP message and UL-MAP message, the DL-MAP message and UL-MAP message are transmitted after being modulated and encoded in accordance with the most robust Modulation and Coding Scheme (MCS) level from among MCS levels usable in the communication system.
Further, a Transmit/Receive Transition Gap (TTG) 180, which is a guard region, is inserted between the DL sub-frame and the UL sub-frame, and a Receive/Transmit Transition Gap (RTG) 190 is inserted between frames.
FIG. 2 illustrates a structure of a frame supporting various transmission methods in a conventional communication system. The example shown in FIG. 2 corresponds to a frame structure used for sequentially transmitting a plurality of zones according to a time division multiplexing scheme.
Referring to FIG. 2, the frame includes a plurality of zones. Specifically, the frame includes a preamble zone 210, a Partial Usage of Sub-channels (PUSC) zone 220, a Full Usage of Sub-channels (FUSC) zone 230, a Tile Usage of Sub-channels (TUSC) zone 240, a band Adaptive Modulation and Coding (AMC) zone 250, and an Adaptive Antenna System (AAS) zone 260.
The PUSC zone 220 to the AAS zone 260 are discriminated from each other according to the sub-channel allocation scheme of the frame, and information related to the zones is transmitted in the MAP area within the DL frame 100 of FIG. 1.
As described above, in the conventional structures, the base station transmits a preamble at each frame and supports multiple transmission schemes according to a time division multiplexing scheme. Therefore, the conventional structures inevitably have an increased MAP size and increased system overhead.